In the current year (1980-81) two-dimensional ultrasound will be combined with pressure and flow data to analyze problems in clinical and experimental physiology associated with cardiac surgery. Intraoperative studies in humans will concentrate on development of accurate regressions for calculation of left ventricular mass and volume based on an algorithm employing three short axis views and one long axis view produced by two-dimensional ultrasound with a sterilized transducer. RAO angiography preoperatively filmed with a calibration grid and analyzed by the area-length method will serve as the standard for comparison. Data will also be accumulated for calculation of left ventricular systolic mechanics to analyze effects of surgery on left ventricular performance. A computerized spherical model of the left ventricle is used, the data input being LV mass, EDV, LVP, dp/dt, and instantaneous stroke volume. Laboratory studies will move beyond the validation studies, which have been completed, to study effects of four parameters on left ventricular compliance in dogs on cardiopulmonary bypass. The parameters to be studied are: regional ischemia, temperature, arterial pressure, and heart rate. Studies of acute and chronic effects of cardiac surgery on left ventricular mass, end-diastolic volume, and ejection fraction will be pursued.